-40 70 2500 20 (2500) (1000) 40 MINIMUM DESIGN LOADS (700) 40 CS (1700 (800) 1200) (700 HOO 500) (500) 50 1900) 50 (600) 80 (500) TO 2.1 GENERAL Buildings and other structures shall be designed using the provisions of either Section 2.3 or 2.4. Where elements of a structure are designed by a particular material standard or specification, they shall be designed exclusively by either Section 2.3 or 2.4. 2.2 SYMBOLS A = load or load effect arising from extra ordinary event A D = dead load D; weight of ice = E = earthquake load F = load due to fluids with well-defined pressures and maximum heights flood load Fa H = load due to lateral earth pressure, ground water pressure, or pressure of bulk materials L = live load L, roof live load R = rain load S = snow load T = self-straining load W wind load W; wind-on-ice determined in accordance with Chapter 10 2.3 COMBINING FACTORED LOADS USING STRENGTH DESIGN 2.3.1 Applicability The load combinations and load factors given in Section 2.3.2 shall be used only in those cases in which they are specifically authorized by the appli- cable material design standard. 2.3.2 Basic Combinations Structures, components, and foundations shall be designed so that their design strength equals or exceeds the effects of the factored loads in the following combinations: 1. 1.4D 2. 1.2D 1.6L + 0.5(L, or S or R) 3. 1.2D 1.6(L, or S or R) + (L or 0.5W) 4. 1.2D 1.0W+L+ 0.5(L, or S or R) 5. 1.2D 1.0E+L+ 0.2S 6. 0.9D1.0W 7. 0.9D+1.0E EXCEPTIONS: 1. The load factor on L in combinations 3, 4, and 5 is permitted to equal 0.5 for all occupancies in which L, in Table 4-1 is less than or equal to 100 psf, with the exception of garages or areas occupied as places of public assembly. 2. In combinations 2, 4, and 5, the companion load S shall be taken as either the flat roof snow load (p) or the sloped roof snow load (p.). Where fluid loads F are present, they shall be included with the same load factor as dead load D in combinations 1 through 5 and 7. Where load H are present, they shall be included as follows: 1. where the effect of H adds to the primary variable load effect, include H with a load factor of 1.6; 2. where the effect of H resists the primary variable load effect, include H with a load factor of 0.9 where the load is permanent or a load factor of 0 for all other conditions. Effects of one or more loads not acting shall be investigated. The most unfavorable effects from both wind and earthquake loads shall be investigated, where appropriate, but they need not be considered to act simultaneously. Refer to Section 12.4 for specific definition of the earthquake load effect E.' Each relevant strength limit state shall be investigated. 2.3.3 Load Combinations Including Flood Load When a structure is located in a flood zone (Section 5.3.1), the following load combinations shall be considered in addition to the basic combinations in Section 2.3.2: 1. In V-Zones or Coastal A-Zones, 1.0W in combina- tions 4 and 6 shall be replaced by 1.0W + 2.0F. 2. In noncoastal A-Zones, 1.0W in combinations 4 and 6 shall be replaced by 0.5W + 1.0Fa 'The same E from Sections 1.4 and 12.4 is used for both Sections 2.3.2 and 2.4.1. Refer to the Chapter 11 Commentary for the Seismic Provisions. 7 |